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Toxic Plants and Herbs.



On this page you will find the plants and herbs that ARE TOXIC to human. Please DO NOT in any way or for any reason consume these plants.

These dangerously poisonous plants listed below all contain toxic chemicals that can cause serious illness or even death. I was in two minds as to whether to add these pages, as I did not want to advertise their properties, but I decided to go ahead anyway. I wanted to make you all aware the ill effects of these plants and herbs, and show the symptoms of their poisonings, just in case, that one day it could help you save a life.

If you are not sure of the plants properties, it is wise best to leave well enough alone. Please use the old phrase, "Better safe than sorry", when you are in doubt.



Common Names:

Botanical Names:



(also known as Bugloss)

Anchusa officinalis L.

There is evidence that alkanet may cause cancer if taken internally over a long periods of time.


(also known as Root of the Holy Ghost, Garden Angelica)

Angleica archangelica L.

Positive identification is essential when collecting the wild species because it resembles some poisonous members of the carrot family, most notably poison hemlock.

Apple of Sodom

(also known as Devil's apple, poison apple)

Solanum linnaeanum

All parts of this plant are poisonous, but the yellow fruits are extremely poisonous


(also known as leopard's bane, mountain tobacco)

Arnica montana

All parts of this fresh plant are poisonous. Do not use internally as there is evidence that arnica preparations affect the heart. When ingested this can cause painful irritations of the stomach, intestines and is also very toxic to the heart and can also dangerously increase blood pressure. But the manufactured products are usually quite safe for external use.


(also known as Deadly Nightshade, Dwale, Fair Lady)

Atropa belladonna

The chemical substance atropine in this herb dilates the pupils. Scopolamine or hyoscine, and hyoscyamine are very dangerous. The leaves and root are the most poisonous. This plant is extremely toxic; even in small doses of it can cause coma and death. Because of the ripe berries are not only sweet-tasting but poisonous, children should be expressly warned not to touch them.

Bird's Foot Trefoil

Lotus corniculatus

Leaves and flowers contain cyanide, which may cause paralysis, convulsions, coma and death.

Bittersweet Nightshade

(also known as Felonwort, Woody Nightshade)

Solanum dulcamara

The whole plant is poisonous and can only be prescribed by practicing physicians.

Black Locust

(also known as False Acacia, Locust Tree, White Acacia)

Robinia pseudoacacia

The smooth dark brown pods which are about 8-10 cms long contains poisonous seeds that can cause vomiting, nausea and dizziness and may dangerously slow the heart beat.

Black Mustard

Brassica nigra

A powerful irritant, mustard oil should be used sparingly, in diluted form, and only externally, for short exposure periods.

Blackberry Nightshade

Solanum nigrum L.

The leaves and green fruits are highly poisonous.


(also known as wild pineapples)

Macrozamia communis L.

The fruits, seeds and leaves of this plant are all poisonous. Australian farmers have eradicated the palm-like tree in many regions as the poisons if ingested by livestock, cause the debilitatin disease known as "staggers".


(also known as Caraway seed)

Carum carvi L.

Positive identification is essential in order not to confuse the plant with such poisonous members of the carrot family as poison hemlock.

Carolina Jasmine

(also known as Evening Trumpet Flower, Woodbine, Yellow Jessamine)

Gelsemium sempervirens

All parts of Carolina jasmine contain toxic alkaloids that can cause paralysis and death and none must be taken internally.

Castor Oil Plant

(also known as Castor Oil Bean)

Ricinus communis

The tiny pale flowers are followed by spiny three-lobed capsules which split when ripe to eject the shiny mottled seeds. The seeds contain extremely toxic ricin and should not be swallowed.

Caustic Bush

(also known as Caustic Vine, Milk Bush, Milk Vine, Snake Plant)

Sarcostemma australe R. Br.

All parts are poisonous if applied to eyes, sensitive skin or taken internally.


(also known as Swallow Wort, Tetterwort)

Chelidonium majus L.

The juice can cause severe irritation of the mucous membranes and is also a central nervous system depressant. Skin irritation results from handling crushed parts of the plant.

Chinese Lantern

(also known as Bladder Cherry, Strawberry Tomato, Winter Cherry, Ground Cherry)

Physalis alkekangi L.

When mature the lantern contains a red fruit resembling a cherry. Unripe fruit may be toxic and the ripe fruits eaten in large quantities can cause diarrhoea.


(also known as Coughwort, Son-before-the father)

Tussilago farfara L.

Laboratory tests on rodents indicate that coltsfoot may cause cancer if taken in large doses or repeated small doses. Do not use this herb internally.


(also known as Ass-ear, Blackwort, Bruisewort, Healing herb, Knitback, Knitbone)

Symphytum officinale

There is evidence that comfrey may cause cancer if taken internally over a long period of time.

Common Box

(also known as Boxtree, Boxwood)

Buxus sempervirens L.

The leaves contain poisonous substances and have caused animal deaths.

Common Fumitory

(also known as Earth-smoke, Hedge fumitory, Wax Dolls)

Fumaria officinalis L.

Large doses cause stomach aches and diarrhoea.

Common Groundsel

(also known as Common ragwort, Ground glutton, Grundy swallow)

Senecio vulgaris L.

There is evidence that groundsel may cause liver cancer if taken internally over a long period of time.

Common Oleander

Nerium oleander L.

All parts are highly poisonous and many deaths have been caused by the ingestion of leaves, flowers, bark and roots. People have fallen unconscious after inhaling smoke from the burning timber, and poisonings are even said to have occurred as a result of food being stirred with the twigs. All part of the plant ooze thick milky sap when cut, and this liquid burns the eyes and mouth. The leaves are eaten by caterpillars of the common crow butterfly, which then become poisonous to birds.

Common Thornapple

(also known as Datura, False Castor Oil, Stramonium)

Datura stramonium

The whole plant is poisonous. Symptoms include dry mouth, dilated pupils, reddening of the face and neck, abnormally rapid heartbeat and delirium. Thronapple may be fatat in large doses.

Crab's Eye

(also known as Jequirity Bean)

Abrus precatorius

Small mauve pea-sloers appeart on short spikes followed by pods 3-5 cms and each containing several smooth ovoid seeds, scarlet with a black patch at one end. Seeds are extremely poisonous and must not be taken internally.


(also known as Lent Lily)

Narcissus pseudonarcissus L.

Daffodil bulbs, sometimes mistaken for onions, are toxic and may cause death. Symtoms include salivation, vomiting and contraction of the pupils.


(also known as Dillseed, Dillweed)

Anethum graveolens L.

Positive identification is essential in order not to confuse the plant with such poisonous members of the carrot family as poison hemlock.


(also known as Bourtree, Pipe Tree, European Elder)

Sambucus nigra

The leaves, bark and roots of some elders, including American elder, contain poisonous alkaloids and should not be used internally.

English Broom

(also known as Broom Tops, Scotch Broom)

Cytisuus scoparius L.

Therapeutic Goods Administration in Australia lists English Broom as unsafe.

English Ivy

(also known as True Ivy)

Hedera helix L.

The berries and large quantities of the whole plant may cause poisoning.

English Yew

Taxus baccata L.

All parts of ALL yews are poisonous. The leaves and seeds contain taxine, a heart-stopping alkaloid that has killed many children..


(also known as Ergot of Rye)

Kavuceos purpurea

Do not take internally. An overdose can be fatal; smaller doses produce abortions, convulsions and gangrene.

European Mountain Ash

(also known as Quickbeam, Rowan Tree)

Sorbus aucuparia L.

The fruits are reported to contain a compound, parasorbic acid, which causes cancer. There is some evidence that they may be toxic to children.


(also known as Rose-noble, Scrofula plant, Squarestalk, Stinking Christopher, Throatwort)

Scrophularia nodosa L.

All part of the herb Figwort are not considered safe for internal use except under close medical supervision.


(also known as Linseed, Lint Bells)

Linum usitatissimum L.

Immature seed pods can cause poisoning.


(also known as Scorpion Grass)

Myosotis scorpioides L.

There is evidence that forget-me-not may cause liver cancer if taken over a long period of time.


(also known as Deadmen's Bells, Witch's Bells)

Digitalis purpurea

 Extremely poisonous. A leaf chewed and swallowed may cause paralysis and sudden heart failure.

Giant Stinging Tree

Dendrocnide excelsa

Hairs on the leaves, stems and fruits sting very painfully. This plant delivers excruciating pain when its stems or leaves - even foliage - are touched.


(also known as Pearl Plant, Stoneseed)

Lithospermum officinale L.

All parts of the plant Gromwell is highly toxic and should not be taken without medical supervision.

Guelder Rose

(also known as Cranberry bush, Cranberry Tree, Cramp Bark, Whitten Tree, Snowball Tree)

Viburnum opulus L.

The uncooked berries are poisonous, causing severe gastrointestinal disturbances.

Gutta Percha Tree

(also known as Mangrove, Manyingila)

Excoecaria parvifolia

Gutta percha should not be taken internally. The milky sap is extremely poisonous and should be kept away from the eyes. Mouth and sensitive skin.


Conium maculatum L.

All parts are poisonous, especially the seeds and roots. The leaves emit a sour mousy odour when crushed, the stems are noticable by their purple spots or blotches. Many people have been fatally poisoned by this plant.


(also known as Black Henbane, Devil's Eye, Hog Bean, Jupiter's Bean, Poison Tobacco, Stinking Nightshade)

Hyoscyamus niger

The use of henbane is restricted by law in Australia. It is an extremely dangerous poison; it can cause dizziness, stupor, blurred vision, delirium, convulsions and, in large amounts, even death.

Herb Mercury

(also known as Annual Mercury, Boys-and-Girls, Mercury)

Mercurialis annua L.

Herb Mercury is a strong lacative and may cause severe gastroenteritis.

Horse Chestnut

(also known as Buckeye)

Aisculus hippocastanum

The prickly green seed pods mature in autumn when they split open to release one to three seeds or nuts. There are reports that children have died from eating the nuts.


(also known as Dwarf juniper, Ground juniper)

Juniperus communis L.

The berries (and products from) should be avoided by pregnant women and persons with kidney disease.


(also known as New Zealand Pepper Tree)

Macropiper excelsum

The constituent myristicin found in the leaves can be dangerous if taken in large quantities.


(also known as New Zealand Laburnum)

Sophora tetraptera

The bright yellow flowers appear in drooping clusters. The fruits are long, brown pods with the appearance of a string of beads. All parts of Kowhai are poisonous; the seeds especially should not be consumed.


(also known as Rocket Larkspur)

Delphinium ajacis L.

In Europe and the United States, Larkspurs frequently cause the death of livestock that accidentally eat them while grazing. They contain poisonous compounds related to those of aconite. 


Lavendula officinalis

Lavender oil is an irritant and should therefore not be taken internally.

Lily of the Valley

(also known as Ladder-to-Heaven, Lily convalle, May lily, Our-Lady's Tears)

Convallaria majalis

 The National Health and Medical Council of Australia and the National Poison Centre in New Zealand list this plant as toxic.


(also known as Sea Parsley)

Levisticum officinale

Do not confuse lovage with such poisonous members of the carrot family as water hemlock, poison hemlock and fool's parsley.


(also known as Bhang, Ganja, Grass, Hashish, Hemp, Mary Jane, Pot, Reefer)

Cannabis sativa L.

Do not use except under a doctor's supervision. Smoking or eating marijuana may have physically and psychologically injurious effects.

Marsh Marigold

(also know as American Cowslip, Kingcup, May Blob)

Caltha palustris

Do not eat the raw leaves; they can cause violent gastritis and are toxic to the heart. External application of the leaves can cause blistering.


(also known as King's-Clover, Sweet Clover, Sweet Lucerne, Yellow Melilot, Yellow Sweet Clover)

Melilotus officinalis

Rotted Melilot is and anticoagulant that causes heamorrhaging in animals. Melilot that has not rotted is quite safe.

Mexican Tea

(also known as Antweed, Jesuit Tea, Stinking weed, Wormseed)

Chenopodium ambrosioides

All parts of the plant may be fatal. Symptoms include nausea, dizziness, convulsions and paralysis

Milky Pine

(also known as Bitter bark, Devil's tree, Dita Bark, White Cheesewood, White pine, Whitewood)

Alstonia scholaris

The sap from the bark or leaves amy have toxic effects; it should be used with great caution.


(also known as aconite and wolfsbane)

Aconitum napellus L.

All parts are poisonous. The roots yield the highly toxic alkaloid aconitine. People have died a very quick death after using this herb and cattle and horses have succumbed after browsing the leaves and flowers.

Northern Pandanus

(also known as Breadfruit, Pandanus Palm, Screw Palm, Screw Pine)

Pandanus spiralis

The wedge-shaped, orange-red fruits are borne in large clusters. The raw fruit of the pandanus burns the mouth and throat when chewed.


Allium cepa L.

The onion can cause severe anaemia if eaten in excessively large quantities.

Opium Poppy

Papaver somniferum

Opium is physically and psychologically addictive. It is a prohibited plant in Australia and New Zealand.


Petroselinum crispum

Parsley should not be used in large quantities during pregnancy as the apiole in one of the plant's essential oils has oestrogenic effects.


Mentha pulegium

Large doses taken internally produce convulsions and coma, and may cause severe liver damage.

Petty Spurge

(also known as Cancer Weed, Milkweed, Radium Plant, Wart-weed)

Euphorbia peplus L.

The milky sap is toxic, particularly when in contact with the eyes, causing inflammation and temporary blindness. It should never be taken internally.


(also known as Munyeroo, Portulaca, Purslane)

Portulaca oleracea L.

Pigweed may cause oxalate and nitrate poisoning if taken in sufficiently large quantities.

Pink Periwinkle

(also known as Madagascar Periwinkle)

Catharanthus roseus

Pink Periwinkle should not be used as a home remedy; it contains powerful anticancer alkaloids which may produce serious side effects.


Duboisia hopwoodii

Concentrated dosages of pituri may have serious narcotic effects.

Prickly Poppy

(also known as Devil's Fig, Mexican Poppy, Thorn Poppy, Yellow Thistle)

Argemone mexicana

The spiny toothed leaves are stalk-less and often blotched with white. Yellow or orange flowers are followed by prickly seed pods. Prickly poppy and its seeds are most poisonous if taken internally and may cause oedema and glaucoma.


(also known as Common Privet, Prim)

Ligustrum vulgare L.

It has numerous white flowers followed by black berries. Do not take internally. The fruits and leaves can cause gastrointestinal irritation and liver damage, and may lower blood pressure.

Queen Anne's Lace

(also known as Bee's nest, Bird's nest, Devil's Plague, Wild Carrot)

Daucus carots L.

Do not confuse Queen Anne's Lace with bishop-weed (Ammi majus) or poison hemlock (Conium macaulatum). Daucus carota has a central red or purple flower.

Queensland Black Bean

(also known as Moreton Bay Chestnut)

Castanospermum australe

Scarlet and yellow pea-like flowers appear in clusters along the branches followed by large green bean like pods, each containing three to six massive seed. The seeds can cause severe diarrhoea and vomiting if eaten without preparation to remover the poisonous saponins and alkaloids.

Redhead Cotton Bush

(also known as Blood Flower)

Asclepias curassavica

This plant should not be taken internally as it contains poisonous glycosides.


(also known as Old Man)

Rosmarinus officinalis L.

The undiluted oil of rosemary shoudl never be taken internally.


(also known as common Rue, Garden Rue, German Rue, Herb-of-Grace)

Ruta graveolens L.

Rue may cause mild poisoning; even handling the fresh leaves may cause the skin to blister. Pregnant women especially should not take rue internally.

Scarlet Rhus

(also called the Japenese wax tree or Sumuch)

Toxicodendron radicans L.

This plant irritates the skin when touched. You can suffer swellings and severe skin irritations. Sensitivity does increase over years too.


(also known as Blue Pimpernel, Blue Skullcap, Helmetflower, Hoodwort, Mad-dog Skullcap, Madweed)

Scutellaria lateriflora L.

Large doses may cause giddiness, confusion, twitching and stupor.


(also known as Bouncing Bet, Bruisewort, Fuller's Herb, Latherwort, Old-maid's-pink)

Saponaria officinalis

If taken internally, soapwort may cuase severe vomiting and diarrhoea.


(also known as Garden Sorrel, Greensauce, Soursuds)

Rumex acetosa

Sorrel contains oxalic acid and can be dangerous to small children, old people or persons in delicate health. It should be parboiled before cooking. The medicinal tea may be poisonous in large doses.

Southern Kangaroo Apple

(also known as Poroporo)

Solanum aviculare

Except for the ripe berries, which are pale orange or yellow, egg-shaped berries fill with tiny flat seeds. all parts of the Southern Kangaroo Apple are highly poisonous.

Southern Sassafras

(also known as Black Sassafras)

Atherosperma moschatum

The use of southern sassafras in Australia is under discussion by the Therapeutic Goods Administration, due to presence (in the bark) of safrole, which is known to be a carcinogen.


(also known as European Spindletree)

Euonymus europaeus

All parts of this tree contain violent laxative properties, and should not be taken internally without professional advice.

St John' s Wort

(also known as Amber Touch-and-Heal, Goatweed, Rosin rose)

Hypericum perforatum

Drinking the flower tea can cause skin blistering.

Sweet Flag

(also known as Clamus, Flagroot, Sweet cane, Sweet grass, Sweet rush)

Acorus calamus L.

Therapeutic Goods Administration of Australia considers Sweet Flag to be carcinogenic.

Sweet Violet

(also known as Blue Violet, English Violet, Sweet-scented Violet)

Viola odorata

Large doses of sweet violet root cause nausea and vomiting.

Sweet Woodruff

(also known as Waldmeister)

Galium odorata L.

The tea in large doses may cause dizziness and symptoms of poisoning, such as vomiting.


(also known as Common Thyme, Garden Thyme)

Thymus vulgaris L.

Excessive use of oil of thyme may cause gastroinestinal disorders.

Viper's Bugloss

Echium vulgare L.

Viper's bugloss taken internally for a prolonged period of time may cause liver damage.


(also known as English Wallflower, Handflower)

Cheiranthus cheiri

Do not use except under a physician's directions.

Water Cress

(also known as Water Nasturtium)

Nasturtium officinale L.

Wash watercress thoroughly before eating it; avoid plants growing in polluted water.

White Cedar

Melia azaderach L.

The fruits are very poisonous. Native to Australia, Asia and Africa. It has sprays of lilac flowers, which develop into green fruits then ripening and dropping as yellow fruits, where children have died after eating them.

White Mustard

Sinapis alba L.

Mustard plasters require careful application; if the plaster is too strong or is left on too long, severe blistering can result.

Winter Cress

(also known as Herb of St Barbara, Upland Cress, Yellow Rocket)

Barbarea vulgaris

Do not use the plant for any purpose internally; recent tests suggest winter cress may produce kidney malfunction in animals.


Gaultheria procumbens L.

Oil of wintergreen is poisonous except in small amounts. Children have died after drinking the oil.


Acokanthera oblongifolia

The leaves, bark and fruit are poisonous. A native of southern Africa. The stems ooze milky sap when cut - this too is poisonous. The starry fragrant flowers turn into succulent reddish or purplish-black fruits.


(also known as Hogweed, Knotweed)

Polygonum aviculare L.

Cook wireweed before eating it; raws wireweed can cause intestinal disturbances. Do not confuse with smartweed, a relative with an acrid taste.

Witch Hazel

(also known as Snapping Hazel, Virginian Witch Hazel, Winterbloom)

Hamamelis virginiana L.

Witch Hazel contains strongly astringent properties and , therefore, should be used with care.

Wood Sorrel

(also known as Shamrock, Sour Trefoil, True Wood Sorrel, White Wood Sorrel)

Oxalis acetosella L.

Leaves contain oxalic acid, which may cause diarrhoea, kidney stones, kidney failure or haemorrhaging if taken internallyin very large amounts.


(also known as Absinthe, Absinthium, Green Ginger, Madderwort)

Artemisia absinthium

Wormwood can cause poisoning. Take only under professional supervision.

Yellow Flag

(also known as Water Iris, Yellow Iris, Yellow Water Flag)

Iris pseudacorus L.

The rhizome and root of yellow flag, if taken in large amounts, may cause stomach and intestinal pain, nausea and vomiting.

Yellow Oleander

Theveria peruviana

All parts are poisonous, the seeds in particular. The flowers mature into apricot-sized fruits, which turn from green to shiny black. One of the toxins produced by the plant, a cardiac glycoside called Thevetin A, has been tried as a drug, but its effects are too dangerous for therapeutic use.